MSVC symbol demangler fails to demangle most templated names

The way I read https://github.com/avast-tl/retdec/blob/7cad5076c06bbe99f410c98a9af8f08d73eb3175/src/demangler/extgrammars/gramatika-ms, the demangler will only expect template arguments in names starting with `??`. This doesn't match the description on https://en.wikiversity.org/wiki/Visual_C%2B%2B_name_mangling and won't demangle names like `?xyz@?$abc@V?$def@H@@PAX@@` which the undname command line tool demangles just fine.

Start in src/demangler/extgrammars/gramatika-ms and inspect how template arguments are recognized in MSVC names. Compare that behavior with the documented mangling rules and the undname result for ?xyz@?$abc@V?$def@H@@PAX@@. Done means the grammar also demangles templated names such as the example given.

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